1. Field of the Invention
The present invention is directed generally to a lift device for raising and lowering a cargo cover on a pick-up truck.
2. Description of the Background
It is common for pick-up trucks to be modified to include a cover over the pick-up truck's cargo bed. Those covers are typically referred to as cargo covers or tonneau covers, and they have many uses, such as protecting items in the cargo bed from elements like rain and snow, preventing items in the cargo bed from being lost during transport, and securing items in the cargo bed from would-be thieves.
Some cargo covers are nothing more than a large sheet of rigid or flexible material, that must be manually installed and removed from the cargo bed. Many cargo covers include one or more access doors, that allow for access to the cargo bed without removing the cargo cover. Still other cargo covers are pivotally attached to the cargo bed, typically at the edge of the cargo bed near the cab of the truck, so that the cargo cover may be opened to allow access to the cargo bed. Some cargo covers also include gas-charged cylinders to assist in opening the cargo cover for access to the cargo bed. Some cargo covers even include fluid-operated cylinders, gas or hydraulic, to open the cargo cover at the press of a button.
The prior art cargo cover lift mechanisms have several deficiencies attributable to the lift mechanisms used to raise the cargo covers. Those mechanisms typically include two or more fluid-operated cylinders spaced to equally share the burden of lifting the cargo cover. Each cylinder is attached at one end to the cargo bed and is attached at another end to the cargo cover. It is well known that the construction of such cylinders limits their expanded length to approximately twice their compressed length. Fluid assisted cargo covers that are hinged along one edge will typically include cylinders near either the hinged edge or near the opening edge. If the cylinder is located near the opening edge, it will usually open the cargo cover a distance approximately equal to the depth of the cargo bed, creating a relatively narrow opening in the cargo cover. In contrast, if the cylinders are located near the hinged edge, they will allow the cargo cover to open significantly more, but will require larger gas or hydraulic pumps and larger cylinders to compensate for a loss in leverage caused by lifting the cargo cover near its pivot point. Larger pumps and cylinders are more expensive, heavier, and require more space in the cargo bed.
Thus, the need exists for a small lift device that provides for wide opening of the cargo cover.